Dry fractionation and crystallization kinetics of high-oleic high-stearic sunflower oil

Fractionation of fats and oils makes it possible to generate products with specific properties from natural fats that contain a variety of triacylglycerol (TAG) species. High-oleic high-stearic (HOHS) sunflower oils contain high levels of saturated fatty acids, mainly stearate, on a high-oleic background. Accordingly, HOHS oils could be a source of disaturated TAGs appropriate for cocoa butter equivalent formulations. We examined the kinetics of HOHS oil crystallization, paying special attention to the influence of crystal seeding and temperature on the process and the composition of the final fractions. This oil was fractionated at 18 °C, and seeding increased the amount of disaturated TAGs recovered in the precipitate from 23% to up to 30%. The experimental data collected were fitted using the models of Gompertz and Avrami to study how well these models fitted the data and their utility in predicting the progress of crystallization. At seeding additions above 0.25% there was a change in the crystallization mechanism that improved the process of fractionation. The effect of temperature was also studied, showing important increases in the maximum rates of crystallization when fractionations were carried out at lower temperatures. Finally, the melting profiles of the fractions enriched in saturated fatty acids were studied, showing amounts of solids intermediate between the initial oil and cocoa butter. © 2011 AOCS.This work was supported by the Ministerio de Ciencia e Innovación and FEDER, project AGL2008-01086/ALI.Peer Reviewe